1. Field of the Invention
This invention relates in general to control systems for opening aerodynamic decelerators such as parachutes and the like, and in particular to aerodynamic decelerator opening control systems that are operated by remote command.
2. Description of Related Art
Skydiving is a sport that requires extensive training to master. One type of training involves a series of free falls that a student, accompanied by instructors, must execute in a manner that satisfies established guidelines. In these free falls, the student is required to open his parachute by pulling his ripcord on his own initiative, or at his instructors' signal. If he fails to react accordingly within a brief time period, an instructor then reaches out to the student's ripcord and pulls it for him.
This procedure is risky and dangerous as many events can go wrong. One of the events that can go wrong occurs if a student falls away from the instructors as he jumps out of the airplane. If the student continues to drift away, the instructors may not be able to catch up to the student in time to deploy his parachute if the student does not. Another problem situation arises if a student panics and moves his arms and legs thereby preventing the instructor from reaching the student's ripcord. The time period between leaving the aircraft and reaching the lowest altitude where the parachute must be opened in order to function correctly is approximately one minute, which makes even minor complications extremely hazardous.
Heretofore, most safety devices that incorporate a control system for automatically opening parachutes consist of mechanisms that use elevation and velocity as determining parameters. These devices automatically activate a parachute opening mechanism at preset elevation and velocity conditions. One such device is disclosed in U.S. Pat. No. 3,667,705 to S. L. Snyder. That patent discloses a device that triggers a parachute opening mechanism at a preset elevation relative to the ground level if the parachutist is falling at a velocity greater than a predetermined value. The elevation and velocity values are chosen to trigger the parachute opening mechanism if the parachutist fails to open the parachute himself before descending to a certain altitude.
U.S. Pat. Nos. 3,984,984 and 3,992,999 to F. X. Chevrier et al. disclose devices that pull the ripcord of a skydiver's parachute at a predetermined altitude after they are activated, directly or indirectly, by the skydiver.
U.S. Pat. Nos. 4,858,856 to H. Cloth, and 4,865,273 to L. Jones disclose devices whose functions are similar to that of the patent to S. L. Snyder. Although these devices execute those functions in a different manner, they suffer from the same limitations as that patent.
The problem with devices similar to the ones disclosed in the aforementioned U.S. Patents is that they do not allow an instructor, in a training situation, to open the parachute of a student at the moment he deems it best. These devices are fully automatic and changes cannot be made to their triggering function while they are in flight. If one of these devices is preset to open a parachute at the lowest elevation required for a safe landing, it will not allow a skydiver much time to prepare for landing. A panic stricken skydiver will require addition time to calm down prior to the landing. If, however, the elevation is preset to a level much higher than that required for a safe landing, the device will allow the student fewer opportunities to correct mistakes on his own. The parachute may also open prematurely, endangering the student or the instructors. Furthermore, these devices depend on changes in air pressure to trigger them. If a skydiver is falling in a manner that minimizes the difference in the measured air pressure, such as on his back, the accuracy of these devices may be affected.
It is desirable to provide a device that allows a skydive instructor to open a student's parachute instantaneously and without the need to be in physical contact. No device is known, however, that achieves this function.